Boat



Sept. 8. 1925. 1,553,161

W. A. HICKMAN BOAT Filed Sept. 1924,

Patented Sept. .8 1925 UNITED STATES PATENT OFFICE.

WILLIAM ALBERT HICKMAN, on NEW LONDON, co NEcrIcUzr. I I

BOAT.

Application filed september 25, 1924.. Serial No. 739,838.

To all whom it may concern:

Be it known that 1, WILLIAM ALBERT HICKMAN, a subject of the King of Great .propeller which is so placed that its hub is above or out of contact with the water when the boat is at speed and the blades only traverse the water. The efficiency of this type of propeller, arising principally from the elimination of the drag of the hub and the less eflicient inner portions of the blades, is well known. such propellers hitherto has been to utilize them in pairs, each propeller being driven by its own engine. A more particular pur pose of the present invention is to provide a construction facilitating the use of a single propeller of this type and in particular one which will permit the use of a propeller wheel of small diameter which may be readily turned at the desired speed by an engine of comparatively restricted piston displacement, yet will be eflicient and bring the boat to speed against the comparatively great resistance which it encounters in starting and at low speeds.

My invention will be best understood by reference to the following description of an illustrative embodiment thereof illustrated in the accompanying drawings, wherein:

Fig. 1 is a side elevation of a boat em;

bodying my invention;

Fig. 2 is a-scctlonal outlin on the line of Fig. 1;

Fig. 3 is a plan of the boat; and

Fig. 4c is an enlarged plan of the stern portion of the boat constituting a diagram.

In the example of my invention shown I.

have shown a boat having a hull 5 of the V bottom type and the after portion 7 of the bottom extends in relatively straight lines fore and aft which constitute guiding surfaces forthe water delivered aft. As best illustrated by Fig. 3, the greatest beam of the boat is well forward and th sides draw together as the stern is approached and the The more usual application of hull may terminate in a small transom stern 9.

The propeller ll is mounted on a propeller shaft which extends fore and aft axially of the boat and is hung aft of the stern. By this I mean there is no athwartship wall or other structure extending into or near the water to the rear of the propeller against which water might be thrown by the propeller causing drag on the progress of the boat. It will be understood that the superstructure might extend over the propeller which would nevertheless be aft of the stern in the'sense referred to. The propeller is'mounted at such a height that the blades project below the bottom of the boat at speed and dip into-th water which flows rearward under the bottom 7 .of the boat and functions as a surface propeller in well known manner.

In the passage of the boat through the water" the hull atits portion of greatest beam cuts the water and causes aflow of water aft along the sides of the boat. At relatively slow speeds this wave appears to follow the sides of the boat as indicated in Fig. 4 by the lines marked L. As the speed rises, th boat travels faster and moves away from the waves running aft along the sides which waves move of their own inertia at a definite speed. This is indicated in. Fig. 4 by the lines S. As the speed still further increases we have for a relatively fast speed such a flow'of water as indicated by the lines F and at high speed the flow may appear to be almost directly aft from the forward portion of the boat as indicated by the lines Chen the boat is at rest it displaces a certain amount of water and in startin the propeller 11 may function substantial y as a submerged propeller. As the boat begins to move, the blades of the propeller 11 engage the water below the bottom of the boat and also projecting into the line of the waves moving along the sides of the boat pastthe stern 9 as indicated b the lines L in Fig. 4 engage the water there as well. \Vhen the water is moving as indicated by the lines L. the propeller may still be funcgathers speed driven forward by the propeller in this manner theflow of water below the bottom of the boat may be substan-- tially the same but the flow along the sides I force.

will be as indicated by the lines S. In this case we have the blades of the propeller inner portions of the blade, however, will.

be in the trou h of the water directly aft of the stern of the boat. lVe thus have a surface propeller in the sense that the hub and inner portions of the blades are not operating on the water but the blades engage the water and have a driving function through a considerable portion of their revolution and produce correspondingly more driving Finally, in the case of very speedy boats as the boat obtains high speed and the flow of the water is changed by the speed of the hull, the water, as indicated by the lines H, no longer is thrown into the path of the propeller blades at the sides of the boat which is then driven solely by the blade of the propeller engaging the flow of water proceeding from under the bottom of the boat and rising not very much above the height of the bottom of the stern transom 9.

As the speed of the boat through the water increases, the inertia of the water relative to the speed of the propeller blades greatly increases and if the surface of the propeller engaged were of constant area a relatively larger amount of power would be required to force the propeller blades through the water independently of the resistance of the hull of the boat. In certain types of boat also the resistance in starting the boat and bringing it to speed may be relatively high and this resistance of the boat may be reduced as the boat comes to speed. By the arrangement described it'will be seen that at low speeds when the relative inertia of the water acted upon by the propeller blades is low the propellermay first function substantially as a submerged propeller with all the blades working. As the boat gathers way, the water will be diverted from the hub and inner portions of the blades and the drag of these parts will be eliminated yet the blades in revolving will cut the water through a considerable portion of their rev-- olution and the force developed will be high. Then as the boat comes to speed, a reduced area of the blade will be contacting with the water and the resistancedue to the relatively high inertia of the water will be correspondingly reduced but ample power may nevertheless be developed to propel the boat. An important advantage consists in the abil- -ity to use a propeller wheel of restricted diwater, usually at their lower position, a lateral component of force is developed by the obliquely disposed blade passing through the water which tends to swing or paddle the stern around. This effect is more noticeable at slow speeds when the boat is not moving so rapidly forward and is more easily diverted from the straight course. This paddling action is to an extent minimized by the present construction in that at the slower speeds the propeller is functioning more nearly in the manner of a submerged propeller and the lateral thrust on the stern is minimized. The steering action of the propeller hub may be minimized by carrying a certain amount of helm on the boat, that is, steering by means of a rudder in such a manner as to counteract the tendency of the propeller to throw off the stern.

The rudder 13 is preferably hung directly aft of and in line with .the propeller and in this position it acts with a powerful mechanical advantage at the stern of the boat, I have herein shown the rudder as mounted on a bearing 15 on the end of the propeller shaft and in a bumpkin 17 rigged out from the stern of the boat. By this arrangement a frame-work at or near the surface of the nated. Furthermore, since when the boat is at speed the hub of the propeller is raised to a position above the surface of the water, at the higher speeds the bearing 15 will like wise be raised above the water and there Wlll be no under-water parts to exert a drag on the progress of the boat. Since the rudder for a wide range of speeds is subject to the wash of the waves flowing aft from the sides of the boat, steering is considerably facilitated.

I have described in detail the particular embodiment of my invention shown by way of example in the accompanying drawings in order that the construction thus illustrated might be readily understood. "Qbviously the detailed character of the description has been to promote a ready understanding of the particular example shown and the details of construction may be widely varied without departing from the spirit of the invention.

What I claim as new and desire to secure by Letters Patent I shall express in the following claims:

1. A motor boat having a single semi-submerged or surface propeller aft and a hull having an after portion so narrowing aft as to deliver at relatively low speeds a flow of water along said sides to the blades of the propeller.

2. A motor boat having a hull, the after portion of which has a bottom constructed to constitute a guiding surface for the water and sides drawm together aft and a single surface propeller ung at the stern and having blades adapted to project below said bot tom and also lateral y to engage the flow of water developed by said sides at relatively low s eeds. 3. motor boat having a single semi-submerged or surface propel er hung aft of the stern of the boat on a shaft extending fore and aft and a rudder hung'in the wake of said propeller. I

4. A motor boat havin a single semi-submerged or surface prope ler hung aft of the stern of the boat on a shaft extending fore and aft and a rudder hung in the wake of said propeller and supported at least in part from the end of the propeller shaft. 5. A motor boat having a single semi-submerged or surface propeller hung aft of the stern of the boat on a shaft extending fore and aft and a rudderhung inthe wake of said propeller on the end of the propeller shaft and an above-water support.

6. A motor boat having a semi-submerged or surface propeller aft of the stern and a hull having an after portion narrowing aft and delivering at the slower speeds of the boat, a stream of water to the propeller blades both below and laterally of the hub and a rudder hung in the wake of the propeller and subject to the aotion of said stream.

7. A motor boat having a single semi-submerged or surface propeller hung aft of the stern and a hull formed on lines to deliver to the propeller blades at a normal operating speed for the boat a stream of water below the propeller hub but not rising thereto and streams laterally of the propellerhub but not reaching thereto.

8. A motor boat having a single semi-submerged or surface propeller hung aft of the stern and a hull formed on lines to deliver to the propeller blades at a normal operating s eed for the boat a stream of water below t e propeller hub but not rising thereto and streams laterally of the propeller hub but not "reaching thereto and a rudder in the wakeof the propeller subject to the action of said streams.

. In testimony whereof I have signed my name tothis specification.

WILLIAM ALBERT'HIGKMAN. 

